Method for resource utilization of agroforestry waste

Abstract

The application discloses a kind of agricultural and forestry waste resource processing method, belong to green agricultural waste treatment and biomass energy utilization technical field, this method mixes agricultural and forestry waste with dewatering sludge, adds low eutectic solvent and applies high pressure pulse electric field to carry out synergic pretreatment, realizes lignocellulose dissociation and blocks antibiotic resistance gene horizontal transfer in sludge, pretreated material and zero iron modified biochar are added to high solid anaerobic digestion reactor, realize long-acting passivation of heavy metal and build interspecies direct electron transfer path, based on redox potential and pH dual parameter, combined with closed-loop control adaptive regulation micro-aeration, realize acid control, in-situ desulfurization and ammonia inhibition synergy, this method is suitable for the synergic resource processing of agricultural and forestry waste and sludge.

Description

Technical Field

[0001] This invention relates to the field of green agricultural waste treatment and biomass energy utilization technology, specifically a method for the resource-based treatment of agricultural and forestry waste. Background Technology

[0002] With the continuous advancement of green agriculture and urbanization, the amount of agricultural and forestry waste such as crop straw and forestry branches, as well as municipal sludge, is increasing year by year. The resource-based disposal of these two types of waste has become an urgent problem to be solved in the field of environmental governance. Anaerobic digestion technology can convert organic solid waste into biogas and organic matter products, and is one of the mainstream technical paths for realizing the resource utilization of agricultural and forestry waste and sludge. Mixing agricultural and forestry waste with sludge and carrying out high-solids anaerobic digestion can not only adjust the carbon-nitrogen ratio of the mixture and improve the microbial metabolic environment, but also reduce the reactor volume and increase the gas production efficiency per unit volume. Therefore, it has become a key research direction in the field of co-processing of solid waste. The anaerobic digestion process usually includes four interconnected metabolic stages: hydrolysis, acidification, acetic acid production, and methanogenesis. The functional microbial communities in each stage have different sensitivities to environmental parameters such as pH, redox potential, and temperature, which constitutes the known basis for the design of co-processing technology.

[0003] Currently, the most widely used industrial co-treatment schemes for agricultural and forestry waste and sludge typically include the following steps: First, agricultural and forestry waste such as straw undergoes acid-base-heat pretreatment, i.e., soaking in dilute acid followed by cooking under high temperature and pressure conditions above 120 degrees Celsius to destroy the lignocellulose structure and improve subsequent hydrolysis efficiency. Second, the pretreated material is mixed with dewatered sludge in a certain proportion and added to an anaerobic digestion reactor for absolute anaerobic digestion under mesophilic conditions. The system is maintained in a weakly alkaline range by monitoring the pH value. Finally, the biogas produced is desulfurized and deammonified by conventional methods such as water washing or chemical adsorption and then connected to the grid for utilization. The digested biogas residue is simply dewatered and returned to the field as organic fertilizer. The structure of the above scheme mainly includes a pretreatment device, an anaerobic digestion reactor, a biogas desulfurization and deammoniation device, and a biogas residue treatment unit. The units are connected sequentially by pipelines and pumps. The material flows in a unidirectional flow sequence of pretreatment, anaerobic digestion, biogas purification, and biogas residue disposal. Each treatment unit operates relatively independently and lacks a coordinated control relationship based on real-time operational status feedback.

[0004] The aforementioned existing technical solutions have several technical defects:

[0005] Firstly, the acid-base-heat-high-temperature-high-pressure pretreatment method results in severe equipment corrosion and high energy consumption. Furthermore, during the degradation of lignin in a high-temperature and strong-acid environment, furfural and other byproducts that strongly inhibit methanogens are easily generated, creating a trade-off between the thoroughness of the pretreatment and the subsequent risk of methanogen inhibition.

[0006] Secondly, under high solids conditions, the material viscosity is high and the mass transfer resistance is high. It is difficult to eliminate the local concentration gradient inside the material by mechanical stirring alone. The volatile fatty acids produced during the hydrolysis and acidification stage are prone to accumulate inside the material and cannot be utilized by methanogens in time, which in turn causes a sudden drop in the system pH and a decrease in gas production efficiency.

[0007] Third, existing technologies lack targeted treatment methods for heavy metals and residual antibiotics in sludge. The long-term presence of heavy metals in the digestion system will continuously exert synergistic stress on microorganisms. This stress can easily induce and amplify the horizontal transfer of antibiotic resistance genes, and the two promote each other to form a vicious cycle, resulting in a large number of transferable resistance genes remaining in the digestion products, which leads to ecological safety hazards when returning biogas residue to the field.

[0008] Fourth, existing technologies only treat hydrogen sulfide and ammonia in biogas after digestion, without synergistic source suppression during digestion. This results in high desulfurization and deammoniation costs, along with fugitive greenhouse gas emissions. Summary of the Invention

[0009] To address the shortcomings of the existing technologies, the technical problem this invention aims to solve is: how to simultaneously achieve efficient dissociation of lignocellulose in agricultural and forestry waste, improve the mass transfer efficiency of high-solids anaerobic digestion systems and inhibit acid accumulation, block the source of antibiotic resistance genes and heavy metal complex pollution in sludge and achieve long-term passivation, and synergistic removal of hydrogen sulfide and ammonia from biogas, without significantly increasing pretreatment energy consumption and equipment investment. This overcomes the technical bottleneck of existing technologies that can only treat the above problems in isolation and are difficult to solve in a synergistic way.

[0010] To solve the above-mentioned technical problems, the present invention provides a method for the resource utilization of agricultural and forestry waste, comprising:

[0011] Agricultural and forestry waste and dewatered sludge are mixed at a preset dry basis mass ratio to obtain a mixture. A eutectic solvent prepared from choline chloride and urea at a molar ratio of 1:2 is added to the mixture at a liquid-to-solid ratio. The mixture is thoroughly impregnated and stirred to form a homogeneous impregnation system. This impregnation system is then introduced into a pulsed electric field treatment device. Under set parameters of electric field strength, pulse frequency, and treatment time, a short-term high-voltage pulsed electric field is applied to the impregnation system. During the treatment, the system temperature is maintained between 40°C and 50°C using a temperature control jacket. This allows the depolymerization reaction of lignin molecules, caused by the eutectic solvent breaking hydrogen bonds, to proceed synergistically with the electroporation effect of the pulsed electric field, resulting in a pretreated material containing cell wall-broken sludge and dissociated cellulose. This pretreated material is then fed into a high-solids anaerobic digester for anaerobic digestion. Simultaneously, zero-valent iron-modified biochar is added to the high-solids anaerobic digester. The surface functional groups and nano-zero-valent iron of the biochar adsorb and reduce heavy metal ions in the digestate. Heavy metals are passivated for a long time, and their conductivity is used to construct a direct interspecies electron transport pathway between hydrogen-producing and acetic-producing bacteria and methanogens. Oxidation-reduction potential (ORP) sensors and pH sensors are installed at different heights in the high-solids anaerobic digester to collect ORP and pH signals in real time. After filtering, the signals are normalized and weighted according to preset weights to obtain a composite error signal. The composite error signal is compared with a preset trigger threshold. When the composite error signal is greater than the preset trigger threshold, a proportional-integral-derivative (PID) control algorithm is used to calculate the micro-aeration flow rate control quantity. The calculated flow rate control quantity is then saturated and limited to drive a variable-frequency microporous aeration device to precisely inject a small amount of air into a local area of ​​the reactor. This activates facultative microorganisms and promotes the conversion of hydrogen sulfide in the digestate into elemental sulfur, while inhibiting ammonia volatilization. The ORP and pH signals are continuously monitored. When both return to their respective preset ranges, the injection of micro-air is stopped, forming a complete closed-loop control.

[0012] The method provided by this invention organically couples three technical means: pretreatment dissociation blocking, heavy metal passivation and mass transfer enhancement, and micro-aeration adaptive control, achieving the following beneficial technical effects:

[0013] Firstly, it achieves efficient dissociation of lignocellulose under mild conditions of 40 to 50 degrees Celsius without producing inhibitory byproducts such as furfural. The energy consumption of pretreatment is significantly reduced compared with traditional high temperature and high pressure processes. At the same time, the high-voltage pulse electric field directly destroys the cell membrane of the host bacteria carrying antibiotic resistance genes in the sludge and promotes the release and degradation of intracellular resistance genes, thus blocking the horizontal transfer pathway of antibiotic resistance genes from the source.

[0014] Secondly, by constructing a direct interspecies electron transport pathway through zero-valent iron-modified biochar, the mass transfer bottleneck of the high-solids system is broken, the local accumulation of volatile fatty acids is alleviated, and the methane yield is increased. At the same time, the long-term transformation of heavy metals in sludge from free state to inert solid state is achieved, the stress pressure of heavy metals on microorganisms is eliminated, and the induction effect of heavy metals on the horizontal transfer of resistant genes is blocked, thereby reducing the ecological safety risk of biogas residue for agricultural use.

[0015] Third, by constructing a composite error signal based on the dual parameters of redox potential and pH, combined with proportional-integral-derivative closed-loop control and saturation limiting algorithm, adaptive and precise control of micro-aeration is achieved. Under the premise of not destroying the absolute anaerobic microenvironment of methanogens, acid control, in-situ desulfurization and ammonia volatilization inhibition are achieved in a synergistic and unified manner, reducing the end-of-pipe biogas purification cost.

[0016] Fourth, some of the biogas residue produced by anaerobic digestion is used as raw material to prepare zero-valent iron modified biochar and reuse it in the digestion reactor, forming a green internal cycle of treating waste with waste, reducing the input cost of external functional materials, and improving the efficiency of resource recycling. Attached Figure Description

[0017] Figure 1 This is a flowchart of the overall process for the co-treatment and anaerobic digestion of agricultural and forestry waste and sludge in this invention.

[0018] Figure 2 This is a flowchart illustrating the synergistic pretreatment and resistance gene blocking process using pulsed electric field and eutectic solvent in this invention.

[0019] Figure 3 This is a flowchart illustrating the dynamic control process of adaptive micro-aeration based on the dual parameters of redox potential and pH in this invention. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1-3 The specific embodiments of the present invention will be further described below. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Overall process architecture

[0022] The agricultural and forestry waste resource utilization method provided by this invention mainly consists of the following functional units at the system level: an agricultural and forestry waste pretreatment unit, a sludge pretreatment unit, a pulsed electric field and low eutectic solvent synergistic dissociation blocking unit, a high-solids anaerobic digester with a built-in zero-valent iron modified biochar dosing device and an interspecific direct electron transfer enhancement zone, an online monitoring and adaptive micro-aeration control system composed of a variable frequency microporous aeration device, a programmable logic controller, an oxidation-reduction potential sensor, and a pH sensor, a biogas collection and primary purification unit, and an internal circulation branch for solid-liquid separation of digested biogas residue and partial pyrolysis of biogas residue to prepare zero-valent iron modified biochar for reuse in the digester. The units are connected by material pipelines to realize the sequential flow of materials. The signals collected by the oxidation-reduction potential sensor and pH sensor are processed by the programmable logic controller and fed back to control the opening of the air inlet valve of the variable frequency microporous aeration device, forming a closed-loop control circuit. The biogas residue pyrolysis branch embodies the green internal circulation design concept of treating waste with waste, reducing the input requirements of external functional materials.

[0023] Synergistic pretreatment with pulsed electric field and eutectic solvent and inhibition of resistance genes

[0024] The pretreatment reactor used in this unit is equipped with a material mixing chamber, a eutectic solvent impregnation circulation pipeline, a pair of high-voltage pulse electrode plates respectively connected to the positive and negative poles of a pulse generator, a temperature control jacket, and a stirring paddle. In practice, agricultural and forestry waste is first mechanically crushed to a preset particle size and mixed with dewatered sludge at a preset dry basis mass ratio to obtain the mixture to be treated. Then, a eutectic solvent prepared from choline chloride and urea at a preset liquid-to-solid ratio of 1:2 is added to the mixture, and the mixture is thoroughly impregnated and stirred to form a homogeneous impregnation system. The impregnation system is then introduced into a pulse electric field treatment device, where the electric field strength, pulse frequency, and treatment parameters are set. Under the specified time parameters, a short-term high-voltage pulsed electric field was applied to the impregnation system. During the treatment, the system temperature was maintained between 40 and 50 degrees Celsius using a temperature control jacket. This allowed the depolymerization reaction of the eutectic solvent breaking the hydrogen bonds between lignin molecules to proceed synergistically with the electroporation effect of the pulsed electric field. After pretreatment, an appropriate amount of water was added to the reaction system, causing the dissolved lignin to precipitate due to the change in system polarity, thus achieving solid-liquid separation. The separated eutectic solvent aqueous solution was evaporated and dehydrated before being recycled back to the aforementioned impregnation step. The separated dissociated material, containing cell wall-breaking sludge and dissociated cellulose, entered the subsequent high-solids anaerobic digestion reactor.

[0025] In the above process, the electroporation effect of the pulsed electric field significantly reduces the activation energy and processing time required for the eutectic solvent to break the hydrogen bonds of lignin, thereby achieving efficient dissociation without generating inhibitory byproducts such as furfural. On the other hand, the high-voltage pulse directly acts on the cell membrane of the host bacteria carrying antibiotic resistance genes in the sludge, destroying the cell membrane integrity and causing the intracellular resistance genes to be released into extracellular resistance genes. At the same time, the local electrolysis effect generated by the pulsed electric field can degrade the released extracellular resistance gene fragments, cutting off the horizontal transfer pathway of resistance genes from the source.

[0026] In other embodiments, a eutectic solvent system composed of betaine and glycerol, or a eutectic solvent system composed of lactic acid and mannitol, can be used to replace the choline chloride and urea system. Combined with pulsed electric field synergistic treatment, the dissociation of lignocellulose and destruction of sludge cell membranes can also be achieved under mild conditions. In this case, only the process parameters such as treatment temperature and liquid-solid ratio need to be adjusted according to the physicochemical properties of the replaced eutectic solvent system.

[0027] Long-lasting passivation and mass transfer enhancement mediated by zero-valent iron modified biochar

[0028] This unit is used to prepare zero-valent iron modified biochar and apply it to a high-solids anaerobic digester. Specifically, a portion of the biogas residue discharged from the high-solids anaerobic digester is dehydrated and dried to obtain a dried biogas residue substrate. The dried biogas residue substrate is then impregnated in a ferrous salt solution to fully load iron ions onto the pores and surface of the biogas residue. The loaded substrate is then placed in an oxygen-deficient atmosphere for pyrolysis and pyrolysis, which reduces the loaded iron ions in situ to nano-zero-valent iron particles. Simultaneously, the substrate pyrolyzes to form a porous biochar framework, yielding the zero-valent iron modified biochar product. The prepared zero-valent iron modified biochar is then added to the high-solids anaerobic digester at a preset dosage to participate in the anaerobic digestion process together with the pretreated dissociated material.

[0029] The abundant surface functional groups and nano-zero-valent iron in zero-valent iron-modified biochar undergo surface adsorption and reduction reactions with heavy metal ions in the digestive fluid, achieving long-term passivation of heavy metals. Simultaneously, the conductive particles of zero-valent iron-modified biochar establish conductive bridges between the cell surfaces of hydrogen-producing acetic acid-producing bacteria and methanogenic bacteria, constructing a direct interspecies electron transfer pathway. The above passivation reaction can be represented by the reduction passivation of divalent copper ions by nano-zero-valent iron, as shown in the following reaction equation:

[0030] ;

[0031] In the formula, This indicates nano-zero-valent iron in zero-valent iron-modified biochar. This indicates the presence of free divalent copper ions in the digestive fluid. This indicates the ferrous ions that have been oxidized and entered the solution. The elemental copper that is reduced and deposited on the surface of biochar undergoes a long-term transformation from a free state to an inert solid state through the above reaction, eliminating its stress on microorganisms and thus blocking the induction of horizontal transfer of resistant genes by heavy metals.

[0032] After the interspecies direct electron transport pathway is constructed, acetic acid accumulated during the hydrolysis and acidification phase of the system is converted into methane via this pathway, and the reaction can be represented as follows:

[0033] ;

[0034] In the formula, Acetic acid accumulated during the hydrolysis and acidification stage. and These are methane and carbon dioxide produced by methanogens through direct interspecies electron transport pathways using electron acceptors. This conversion pathway no longer relies on diffusion mass transfer via intermediate carriers such as hydrogen, thus effectively alleviating the problem of volatile fatty acid accumulation caused by limited mass transfer in high-solids systems.

[0035] In other embodiments, commercially available activated carbon, carbon nanotubes, or magnetite particles and other conductive carbon-based materials can be used to replace zero-valent iron-modified biochar as the medium for constructing interspecies direct electron transport pathways. Additionally, heavy metal passivating agents such as phosphate mineralization materials can be added to achieve long-term stabilization of heavy metals. By combining and decomposing the functions of materials, the synergistic effect of enhancing gas production and heavy metal passivation can also be achieved.

[0036] Adaptive dynamic control of redox potential and pH dual parameters for micro-aeration

[0037] This unit is the core control part of the present invention. In specific implementation, online redox potential sensors and online pH sensors are first set at different height positions in the anaerobic digester. The real-time redox potential signal and real-time pH signal of the reactor are collected synchronously at a preset sampling period. The ideal control value of the target control range is set. The collected raw signals are processed by moving average filtering to eliminate the interference of sensor noise and instantaneous fluctuations on the judgment results, and the filtered pH signal and redox potential signal are obtained.

[0038] Subsequently, the filtered pH deviation and redox potential deviation are normalized and weighted according to a set weight to obtain the composite error signal. The calculation formula is as follows:

[0039] ;

[0040] In the formula, for The composite error signal at time 10:00. The preset ideal pH control value, for The measured pH value after time filtering. This is the preset ideal redox potential control value. for The measured redox potential value after time filtering. and These are the weighting coefficients for pH deviation and redox potential deviation, respectively, and their sum is 1. The specific values ​​can be determined by calibration based on the reactor's historical operating data.

[0041] The composite error signal is compared with a preset trigger threshold. If the composite error signal is greater than the preset trigger threshold, it is determined that there is a risk of local acid accumulation in the system, and the micro-aeration rate calculation is initiated. Otherwise, the system is maintained in an absolute anaerobic state, and monitoring continues according to the sampling cycle. After micro-aeration is triggered, the required micro-aeration flow rate is calculated using a proportional-integral-derivative control algorithm. The calculation formula is as follows:

[0042] ;

[0043] In the formula, Let t be the micro-aeration flow rate control quantity calculated at time t. , , These are the proportional, integral, and derivative control coefficients, respectively. The composite error signal obtained from the above calculation has an integral term that is the cumulative integral of the error signal from the initial time to time t, which is used to eliminate steady-state deviation, and a differential term that is the instantaneous rate of change of the error signal, which is used to suppress overshoot.

[0044] To avoid over-aeration disrupting the absolutely anaerobic microenvironment of methanogens, the calculated... Saturation limiting processing is performed to obtain the final execution flow rate sent to the variable frequency microporous aeration device. :when hour, ,when hour, ,when hour, ,in, This is a preset upper limit for the allowable micro-aeration flow rate, used to prevent disruption of the absolutely anaerobic environment. This is a preset lower limit for the effective micro-aeration flow rate, used to ensure the basic oxygen supply required for the activation of facultative microorganisms.

[0045] Programmable logic controllers based on execution flow The opening of the air inlet valve of the variable frequency microporous aeration device is adjusted to precisely inject a trace amount of air into a local area of ​​the reactor, activating facultative microorganisms to degrade residual antibiotics and polymers, and promoting the conversion of hydrogen sulfide in the digestate into elemental sulfur, achieving in-situ desulfurization. At the same time, the introduction of trace oxygen locally inhibits ammonia volatilization. Subsequently, the filtered pH signal and redox potential signal are continuously monitored to determine whether they have returned to their respective preset ranges. If they have returned, the micro-aeration action is stopped and the initial monitoring cycle is returned. If they have not returned, the aeration flow rate is recalculated and adjusted according to the updated error signal until the system returns to stability. The above control process couples the two independent parameters of pH and redox potential into a unified criterion through the composite error signal, and achieves adaptive and precise control of the micro-aeration volume through a closed-loop combined with saturation limiting method. It can strictly protect the absolute anaerobic microenvironment required by methanogens from being destroyed throughout the entire control process, and achieve the synergistic unity of acid control, desulfurization and ammonia suppression. Specific Implementation

[0046] As a specific embodiment of the present invention, the method can be implemented according to the following parameters: Crop straw pulverized to a preset particle size is mixed with dehydrated sludge at a dry basis mass ratio of 1:1 to obtain a mixture with a total solid content of 16%. A eutectic solvent prepared from choline chloride and urea at a molar ratio of 1:2 is added at a liquid-to-solid ratio of 1:3. The mixture is then impregnated and stirred at 45 degrees Celsius for 40 minutes to form a homogeneous impregnation system. The impregnation system is introduced into a pulsed electric field treatment device, and a high-voltage pulsed electric field is applied under the parameters of an electric field strength of 8 kV / cm, a pulse frequency of 200 Hz, and a treatment time of 10 minutes. After pretreatment, water is added at twice the mass of the material. After settling, solid-liquid separation is performed. The separated dissociated material enters a high-solids anaerobic digestion reactor. Simultaneously, zero-valent iron modified biochar is added at 3% of the dry basis mass of the mixture, and the mixture is then stirred at 35 degrees Celsius. Anaerobic digestion was carried out under mesophilic conditions, with the pH control value set at 7.0, the oxidation-reduction potential control value at -300 mV, the pH deviation weighting coefficient at 0.6, the oxidation-reduction potential deviation weighting coefficient at 0.4, the trigger threshold at 0.15, the proportional coefficient at 2.0, the integral coefficient at 0.1, the derivative coefficient at 0.05, and the upper limit and lower limit of the micro-aeration flow rate at 0.5 L / min. Running the method provided by this invention with the above parameters, the volatile fatty acid concentration was maintained within a safe range below 3000 mg / L during a 45-day digestion cycle. The copper and zinc leaching concentrations in the digestate were reduced by more than 60% compared to the control group, the abundance of transferable resistance genes in the biogas residue decreased by more than one order of magnitude compared to before pretreatment, and the hydrogen sulfide concentration in the biogas was reduced in situ. This verifies the feasibility and beneficial effects of the method provided by this invention.

[0047] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for the resource-based treatment of agricultural and forestry waste, characterized in that, Includes the following: Agricultural and forestry waste and dewatered sludge are mixed at a preset dry basis mass ratio to obtain a mixture. A eutectic solvent is added to the mixture and stirred to form an impregnation system. The eutectic solvent is a mixture of choline chloride and urea in a molar ratio of 1:

2. Within a temperature range of 40°C to 50°C, a high-voltage pulsed electric field is applied to the impregnation system to cause the depolymerization reaction of the eutectic solvent to break the hydrogen bonds between lignin molecules and the electroporation effect of the pulsed electric field on the cell membrane of the host bacteria in the sludge to proceed in synergy, so as to obtain a pretreated material containing cell wall broken sludge and dissociated cellulose. The pretreated material is added to a high-solids anaerobic digester for anaerobic digestion. Simultaneously, zero-valent iron modified biochar is added to the high-solids anaerobic digester. The heavy metals are passivated by the adsorption and reduction of heavy metal ions in the digestion liquid by the zero-valent iron modified biochar. The interspecies direct electron transfer pathway between hydrogen-producing acetic acid-producing bacteria and methanogenic bacteria is constructed by the zero-valent iron modified biochar. A redox potential sensor and a pH sensor are installed in the high-solids anaerobic digester to collect redox potential and pH signals in the reactor in real time. The collected signals are filtered and then normalized and weighted according to preset weights to obtain a composite error signal. The composite error signal is compared with a preset trigger threshold. When the composite error signal is greater than the preset trigger threshold, a proportional-integral-derivative (PID) control algorithm is used to calculate the micro-aeration flow rate control quantity. After saturation limiting processing of the micro-aeration flow rate control quantity, the variable frequency microporous aeration device is driven to inject a small amount of air into the high-solids anaerobic digester, so that hydrogen sulfide in the digestate is converted into elemental sulfur and ammonia volatilization is inhibited. The redox potential signal and pH signal are continuously monitored. When both return to their respective preset ranges, the injection of a small amount of air is stopped.

2. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, After applying a high-voltage pulsed electric field to the impregnation system, water is added to the reaction system, causing the dissolved lignin to precipitate due to the change in system polarity, thus achieving solid-liquid separation. The resulting eutectic solvent aqueous solution is evaporated and dehydrated before being recycled for the preparation of the eutectic solvent.

3. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The high-voltage pulsed electric field treatment causes electroporation of the host bacterial cell membranes carrying antibiotic resistance genes in the sludge, prompting the release of intracellular antibiotic resistance genes into extracellular resistance genes, and degrading the released extracellular resistance genes through the local electrolysis effect generated by the pulsed electric field.

4. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The zero-valent iron modified biochar is prepared by the following method: Part of the biogas residue discharged from the high-solids anaerobic digester is dehydrated and dried to obtain a dried biogas residue substrate. The dried biogas residue substrate is impregnated with a ferrous salt solution to load iron ions into the pores and surface of the biogas residue. The loaded substrate was placed in an oxygen-deficient atmosphere for pyrolysis and decomposition, which reduced the loaded iron ions in situ to nano-zero-valent iron particles. At the same time, the substrate was pyrolyzed to form a porous biochar framework, thus obtaining the zero-valent iron modified biochar.

5. The method for resource-based treatment of agricultural and forestry waste according to claim 4, characterized in that, The nano-zero-valent iron in the zero-valent iron modified biochar undergoes a redox reaction with divalent copper ions in the digestion liquid to generate ferrous ions and elemental copper, thereby realizing the transformation of heavy metals from a free state to a solid state.

6. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The composite error signal is obtained by normalizing and weighting the filtered pH deviation and redox potential deviation according to their respective weight coefficients. The pH deviation is the ratio of the difference between the preset pH control value and the measured pH value to the preset pH control value. The redox potential deviation is the ratio of the difference between the preset redox potential control value and the measured redox potential value to the absolute value of the preset redox potential control value. The sum of the weight coefficients of the pH deviation and the redox potential deviation is 1.

7. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The proportional-integral-derivative (PID) control algorithm calculates the micro-aeration flow control quantity based on the proportional term of the composite error signal, the cumulative integral term of the composite error signal from the initial time to the current time, and the derivative term of the instantaneous rate of change of the composite error signal.

8. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The saturation limiting process is as follows: When the calculated micro-aeration flow rate is greater than the preset upper limit of the flow rate, the actual flow rate is set to the upper limit of the flow rate. When the calculated micro-aeration flow control amount is less than the preset lower limit of flow, the actual flow rate is set to the lower limit of flow. When the calculated micro-aeration flow control amount is between the upper limit of the flow rate and the lower limit of the flow rate, the actual flow rate is set to the calculated micro-aeration flow control amount.

9. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The redox potential sensor and the pH sensor are respectively installed at different heights within the high-solids anaerobic digester to synchronously collect redox potential and pH signals at different locations within the reactor during the sampling period.

10. The method for resource-based treatment of agricultural and forestry waste according to claim 1, characterized in that, The agricultural and forestry waste is at least one of straw and forestry branches that have been mechanically crushed to a preset particle size.

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